Field of the Invention
The invention relates to a semiconductor component having a semiconductor body with a terminal pad being connected through an electrically conductive connecting line to a semiconductor function element; a protective element for protecting against electrostatic discharge being connected between the terminal pad and the semiconductor function element; a first supply line for a first supply potential being connected to the semiconductor function element; and a second supply line for the first supply potential being connected to the protective element and being electrically conductively connected to the first supply line.
In semiconductor chips, it is well known for various circuit elements contained in the chip to be supplied with voltage from mutually separate supply lines. That serves the purpose of decoupling the various circuit elements from one another in such a way that fluctuations in the supply voltage, which can be caused, for instance, by switching events, are not coupled into other circuit elements. That provision is employed in large scale integrated semiconductor memories, for instance, in order to separate the voltage supply for driver stages from the voltage supply for the other circuit elements, in particular input buffers. The driver stages are known to draw a relatively high current from the supply voltage, so that because of the not insignificant path resistances and parasitic inductances and capacitances of the supply paths, the supply voltage is briefly reduced during such a current pulse.
Such semiconductor chips also include protective circuits for protecting the inputs or outputs against electrostatic overvoltages and resultant electrostatic discharges (electrostatic discharge (ESD) protective elements). Those elements are connected between the input pad of the integrated circuit and the input or output terminal to be protected, and they assure that when an overvoltage is applied the protective element switches through, and the overvoltage pulse is diverted to a supply voltage conductor track.
In the known semiconductor circuits, the input protective structure is provided in the spatial vicinity of the terminal pad. The terminal pad in turn, because of the relatively high current to be driven, is disposed in the vicinity of the output driver. Consequently, the input protective structure is connected to the supply line from which the output driver is supplied. In general, the connecting line between the protective element and the circuit input has a different line length from the connection between the terminal on the supply potential side of the ESD protective element and the terminal toward the supply potential of the input stage. That connection can certainly include bond connections and terminal pins. In practical cases, the line length for the input signal line is on the order of magnitude of about 1 mm, while the line length through the supply potential path is on the order of magnitude of 10 mm. The path resistance of the path toward the supply potential of the connection between the ESD protective element and the input stage, along with its inductance and its parasitic capacitive effect, are no longer negligible. As a result, the diversion of a voltage pulse in the path toward the supply potential causes a voltage drop. The voltage pulse is consequently not completely dissipated by the ESD protective element. The residual voltage pulse remaining after the ESD protective element then is propagated along the input signal line substantially faster than along the relatively long path of the supply lines that is under the influence of the parasitic elements. As a result, the allowable limit value of the voltage applied to the input stage between the input signal terminal and the supply potential terminal is exceeded, and the circuit element located there is destroyed.